Fuji Sunfire 2.0 FD question

[mexicanmagic]

Hi Guys, I have this bike:
http://www.bikelab.com.au/bike-types/co ... nfire-2-0/" onclick="window.open(this.href);return false;
and find that the FD does not change when under load. Shifts fine when not under load but when climbing invariably the pedals are being pushed.
Bike is in excellent condition and RD works fantastic which is an Alivio.
The FD is a Tourney TX-51 and I'm wondering if I should swap it over for an Alivio - perhaps an M412 or M430 which I've seen online.
I really have no idea on the differences between these models and whether they are a simple swap over and also whether the shifting under load will be better.
Anyone have any advice?
Regards, Joe

[rangersac]

Shifting under full load will more likely than not cause rough shifts or in extreme cases a skipping chain (unless you want to upgrade to Di2 which trumpets about shifting under full power!). You should back off the power a bit until the change is complete. Having said that an Alivio derailleur should do a better job than that Tourney one which is pretty low down on the pecking scale.

[mexicanmagic]

Thanks mate. Would you (or anyone else) know which Alivio FD would swap directly with the TX-51?

[rangersac]

Here at a pretty nice price